Wither regex change?

I just discovered this change between 5.004 and 5.005:

% perl5.004 -le '@a = "abc" =~ /d/; print $#a'
0
% perl5.005 -le '@a = "abc" =~ /d/; print $#a'
-1

Makes sense to me.  Unfortunately I can't find it documented anywhere, and 
I've done the best I can to search the p5p archives and go through the 
Changes files for 5.005.  Does anyone happen to know where it might have 
been documented?  I thought that something with that large an effect would 
have been easily found in the docs, and I was embarrassed not to be able to 
point it out.
--
Peter Scott
Pacific Systems Design Technologies

• Wither regex change? by Peter Scott
• Re: Wither regex change? by Michael G Schwern